Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 248, NWS Phoenix, AZ

September 17, 2021Riverside County, California

NWS Phoenix, AZ issued this flash flood warning at Sep 17, 2021, 3:33 PM PDT for Riverside County, California. It was in force for 5 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Sep 17, 2021, 3:33 PM PDT (22:33 UTC)
Expired: Sep 17, 2021, 8:30 PM PDT
In force: 5 hr
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Riverside County, CA

The radar

The Yuma radar (KYUX), 157 km from the middle of the area, began a volume at 22:32 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

Time	Report	Where	Remark
Sep 17, 6:55 PM PDT	FLASH FLOOD	5 Ne Desert Center, CA	LOCAL LAW ENFORCEMENT REPORTED ROAD CLOSURE DUE TO FLASH FLOODING AT SEVERAL LOCATIONS. SR177 CLOSED BETWEEN RAGSDALE RD. AND SR 62.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

San Diego, CA (KNKX), launched 12:00Z, 10.6 hours before the alert went out and 203 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1121 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 13 m²/s²
0-3 km storm-relative helicity: 47 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

223 
WGUS55 KPSR 172233
FFWPSR
CAC065-180230-
/O.NEW.KPSR.FF.W.0248.210917T2233Z-210918T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
333 PM PDT Fri Sep 17 2021

The National Weather Service in Phoenix has issued a

* Flash Flood Warning for...
  Riverside County in southern California...

* Until 730 PM PDT.

* At 333 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 1.5 inches of 
  rain have fallen. Additional rainfall amounts of 0.5 to 1 inch are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of creeks and streams,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  Desert Center and Eagle Mtn.

This includes the following highways...
	CA Route 177 near mile marker 1...and
	between mile markers 10 and 15...and
	between mile markers 2 and 4.
	CA Interstate 10 between mile markers 101 and 110.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 3368 11548 3384 11551 3395 11546 3394 11530
      3386 11522 3373 11523 3368 11528 3368 11529

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

INS

4 follow-up statements

130 
WGUS75 KPSR 172253
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
353 PM PDT Fri Sep 17 2021

CAC065-180230-
/O.CON.KPSR.FF.W.0248.000000T0000Z-210918T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-
353 PM PDT Fri Sep 17 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 730 PM PDT THIS 
EVENING FOR RIVERSIDE COUNTY...

At 353 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 1.5 and 2 inches of rain have 
fallen. Additional rainfall amounts of 0.5 to 1 inch are possible in 
the warned area. Flash flooding is ongoing or expected to begin 
shortly.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include...
  Desert Center and Eagle Mtn.

This includes the following highways...
	CA Route 177 near mile marker 1...and
	between mile markers 10 and 15...and
	between mile markers 2 and 4.
	CA Interstate 10 between mile markers 101 and 110.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 3368 11548 3384 11551 3395 11546 3394 11530
      3386 11522 3373 11523 3368 11528 3368 11529

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

INS

075 
WGUS75 KPSR 180131
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
631 PM PDT Fri Sep 17 2021

CAC065-180230-
/O.CON.KPSR.FF.W.0248.000000T0000Z-210918T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-
631 PM PDT Fri Sep 17 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 730 PM PDT THIS 
EVENING FOR RIVERSIDE COUNTY...

At 631 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 1.5 and 2.5 inches of rain have 
fallen. Flash flooding is ongoing or expected to begin shortly.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include...
  Desert Center and Eagle Mtn.

This includes the following highways...
	CA Route 177 near mile marker 1...and
	between mile markers 10 and 15...and
	between mile markers 2 and 4.
	CA Interstate 10 between mile markers 101 and 110.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 3368 11548 3384 11551 3395 11546 3394 11530
      3386 11522 3373 11523 3368 11528 3368 11529

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

INS

147 
WGUS55 KPSR 180217
FFWPSR
CAC065-180330-
/O.EXT.KPSR.FF.W.0248.000000T0000Z-210918T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
717 PM PDT Fri Sep 17 2021

The National Weather Service in Phoenix has extended the

* Flash Flood Warning for...
  Riverside County in southern California...

* Until 830 PM PDT.

* At 717 PM PDT, local law enforcement reported several areas of 
  flash flooding occurring along Rice Road north of Desert Center. 
  Between 1.5 and 2.5 inches of rain have fallen. Flash flooding is 
  already occurring.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Law enforcement reported.

  IMPACT...Life threatening flash flooding of creeks and streams,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  Desert Center and Eagle Mtn.

This includes the following highways...
	CA Route 177 near mile marker 1...and
	between mile markers 10 and 15...and
	between mile markers 2 and 4.
	CA Interstate 10 between mile markers 101 and 110.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 3368 11548 3384 11551 3395 11546 3394 11530
      3386 11522 3373 11523 3368 11528 3368 11529

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

INS

115 
WGUS75 KPSR 180327
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
827 PM PDT Fri Sep 17 2021

CAC065-180337-
/O.EXP.KPSR.FF.W.0248.000000T0000Z-210918T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-
827 PM PDT Fri Sep 17 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 830 PM PDT THIS EVENING FOR 
RIVERSIDE COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 3368 11548 3384 11551 3395 11546 3394 11530
      3386 11522 3373 11523 3368 11528 3368 11529

$$

18

The office that day

Everything else NWS Phoenix, AZ issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 17, 2:40 PM PDT	Special Weather Statement	PSR	Riverside	50 min
Sep 17, 3:08 PM PDT	Severe Thunderstorm Warning	PSR	Riverside	52 min
Sep 17, 3:17 PM PDT	Areal Flood Advisory	PSR	Riverside	25 min
Sep 17, 4:11 PM PDT	Special Weather Statement	PSR	Imperial	49 min
Sep 17, 4:25 PM PDT	Special Weather Statement	PSR	Riverside	50 min

Nearby

Flash Flood Warnings in California, 2021 Every flash flood warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.